EJB performance issues migrating from JBoss 4.0.0 to JBoss EAP 4.3.0

Issue

• The same load test completes fine on JBoss 4.0.0 but fails on JBoss Enterprise Application Platform (EAP) 4.3.
• EJB pool sizes not evenly distributed amongst 4 nodes. For 45 concurrent users, our pool sizes grew to 37, 20, 16 and 12.

• The following OutOfMemoryError occurs on the node with the highest pool size (not always the same node):

  11:54:04,738 ERROR [UDP] failed unmarshalling message
  java.lang.OutOfMemoryError: GC overhead limit exceeded
          at org.jgroups.util.Util.readAddress(Util.java:569)
          at org.jgroups.ViewId.readFrom(ViewId.java:134)
          at org.jgroups.View.readFrom(View.java:213)
          at org.jgroups.util.Util.readStreamable(Util.java:692)
          at org.jgroups.protocols.pbcast.GMS$GmsHeader.readFrom(GMS.java:1129)
          at org.jgroups.Message.readHeader(Message.java:711)
          at org.jgroups.Message.readFrom(Message.java:634)
          at org.jgroups.protocols.TP.bufferToMessage(TP.java:977)
          at org.jgroups.protocols.TP.handleIncomingPacket(TP.java:833)
          at org.jgroups.protocols.TP.access$400(TP.java:47)
          at org.jgroups.protocols.TP$IncomingPacketHandler.run(TP.java:1300)
          at java.lang.Thread.run(Thread.java:619)
  

• Heap retention due to multiple org.jboss.remoting.transport.socket.ServerThread objects.